Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
“Internet Telephony” Panel at ICNP ’98 Cormac J. Sreenan Networking and Distributed Systems Research AT&T Labs - Research http://www.research.att.com/~cjs 1 Opportunities Cost reductions – currently service providers can avoid local access charges (3.5c/minute on domestic LD) and costly international settlement fees – transport efficiencies and equipment cost differentials of packet versus circuit – combined administration, customer care, network management, etc Increased flexibility – re-partitioning of functions between network and “intelligent” endpoints – improved user interfaces and modes of communication New applications – arising from use of multi-media, integration with web & email – “click to dial”, virtual secretary , virtual call centers, connected-all-the-time 2 Status: IP Telephony for the Consumer Gateway CO Gateway CO Supports legacy equipment using on/off PSTN gateways – customer establishes account with ITSP or uses calling card – two stage dialing, requires caller to enter account details and phone number – call completed over Internet and/or private IP networks to destination gateway Issues include gateway interoperability, scaling & locating – and establishing service agreements between carriers Bottom line: mono-media, PSTN for access and calling features 3 Status: IP Telephony for Business PBX Gateway Gateway PBX LAN PBX-to-PBX connectivity over corporate intranets – legacy phone/fax calls routed over intranet via gateways – immediate cost reductions by eliminating LD charges – future cost reductions using software-PBX and PC/dedicated packet phones More controlled environment than that of ITSPs – private service over a private network – can simplify or avoid billing, directories, heterogeneity, etc – rely on (software) PBX to provide calling features 4 Consumer Telephony Service for IP Endpoints Non-legacy endpoints enabling full potential of IP telephony Today, callers use a PC telephony application – initiate call to another PC (or a PSTN phone via a gateway) – issues of heterogeneous coding, signaling, directories, addresses, etc – operating system latency and scheduling issues – provides basic “bypass” connectivity for a point-to-point voice call Future can expect a move towards “first-line” service – involvement of large telcos, packet telephony over cable etc – availability of dedicated packet phones, graphical displays Developments in wireless telephony – cellular/PCS infrastructure evolving to IP 5 Issues Going Forward For equipment vendors – scalable gateways, interoperable – low-cost easy-to-use packet phones – scalable conference bridges For service providers – support required user features » call waiting, caller ID, call forwarding, three-way calling, return-call, etc » terminating announcements, operator break-in, 911, operator services – infrastructure for resource accounting and billing – increased predictability, high reliability – infrastructure for settlements and QoS agreements with other carriers 6 Security Impact of perceived security issues associated with Internet Privacy concerns – unauthorized recording or logging of private conversations – anonymous calls requiring hidden caller identification, impact on return-call – desire to hide location information, including IP addresses The law – support for court-ordered wire tap – need to maintain state to allow call tracing Fraud – unauthorized calling, resource usage or call diversion – denial of service attacks 7 Directories and Mobility Directories are required to determine destination network addresses – opportunity for allowing call-by-name features, supporting user mobility – but, removes the flexibility user’s have today : to hide » unpublished number, or selective distribution – therefore need ability for users to provide profiles or call handling logic » who can reach a user, at which places, time and in what manner – issues of profile design, authentication, service scalability – need to continue supporting low-end devices and PSTN interworking Mobility requires mechanisms for updating current location – notion of registration, possibly automatic and long-lived – short-term terminal mobility requires re-routing - Mobile-IP? 8 Some Related Work at AT&T Research Packet wireless devices ATM Telephones To/from PBX gateway IP/ATM Directory server WATSON Speech-to-Text Telephony Over Packet networkS (TOPS) – system architecture for packet telephony using IP/ATM endpoints – directory service with user-programmable call processing logic Wireless Integrated Services Platform (WISP) – platform to explore integrated voice and data to mobile devices – initial focus: scheduled MAC, VC rerouting, low-latency handoffs 9 Conclusions Three key opportunities for IP telephony are: – lower costs due to network efficiencies and new revenue sources – increased flexibility for network operation and service creation – new applications enabled by packet infrastructure and “intelligent” endpoints Status today is mainly supporting legacy endpoints – phone-to-phone via gateways for consumer long distance – PBX-to-PBX interconnection for business voice and fax Technical challenges related to using IP endpoints – services,quality and reliability for a “first-line” service – address security, privacy and authorization issues – provide directories and support for user mobility 10